Tip: There are many different active ingredients when it comes to dandruff shampoos. Zinc, coal tar, salicylic acid, tea tree oil, selenium, and ketoconazole. Some of these are meant to increase the rate of cell turnover (so that scalp clears), while others exfoliate or serve as antifungal remedies. If you haven't gotten any relief within a month, see a dermatologist to discuss cortisone or steroid treatments.
The classic you can trust: Neutrogena T-Gel Shampoo ($7)